1. Field of the Invention
This invention relates to a cargo transport system, and in particular, to a cargo transport system having a container movable within a receptacle such that elevation of the container defines a separate, cargo receiving volume of a commercially attractive capacity adaptable to receive a cargo distinct from the cargo carried by the container.
2. Description of the Prior Art
Waterborne transportation vessels, such as barges, are basically floating box beams having substantially horizontal upper and lower flanges connected by two or more substantially vertical webs. The upper and lower flanges are respectively defined by the barge deck and barge bottom while the webs are defined by the barge side shells. It is common practice in the art to dispose interior members known as the inner bottom and inner longitudinal bulkheads, respectively, in parallel structural relationship to the bottom and to the side shells of the barge. Suitable partitioning and/or load-carrying transverse bulkheads may be transversely disposed between the various longitudinal members. A minimum amount of partitioning is generally required both as a safety measure against sinking due to collision and as a safety measure against overturning due to loss of stability because of what is known in the art as "free surface effect" of liquids contained within the bounding surfaces of the vessel. The "free surface effect" accompanies the presence of any liquid that does not completely fill or "press up" its enclosing space whether it be liquid cargo, water ballast, or bilge water from leakage. An effect similar to that of liquid free surface may accompany cargos that are susceptible to shifting, such as grain.
The minimum number of complete watertight transverse interior bulkheads is usually taken as two, being those necessary as "collision bulkheads" to isolate the forwardmost and the aftmost rake tanks from the remainder of the vessel. The minimum number of longitudinal bulkheads is usually taken as one. Where there is only one longitudinal bulkhead it is almost invariably installed on the centerline of the vessel. In locations where a complete watertight bulkhead is not required, a "swash" bulkhead may be installed which is watertight only from its lower boundaries up to some predetermined height that is less than the full height of the compartment.
In some installations, an interior longitudinal bulkhead may be located in relatively close proximity to the side shell in which case the tank space created adjacent the side shell is known in the art as a "wing tank". The "wing tanks" are typically adapted to receive cargos such as molasses, lard oil, and petroleum products.
The spaces defined by the longitudinal bulkheads (or a longitudinal bulkhead and/or one sideshell and the other sideshell), transverse bulkheads and inner bottom (or bottom shell) may receive bulk cargo such as ores, concentrates, grains, and the like; in special cases the spaces may carry liquid cargo or liquid ballast.
One typical arrangement is known in the art as the OBO, signifying oil-bulk-ore cargo transport. The volume between the inner and outer bottoms may receive liquids such as clear liquid cargo, fuel, potable water, ballast water, or the like. Unloading apparatus, such as augers or conveyors, for transferring cargo from its area may be disposed within the space defined between the cargo and the uppermost bottom plate. If an inner bottom is provided, the unloading apparatus is usually disposed thereabove. If the barge has no inner bottom, the unloading apparatus is disposed above the lower bottom.
There are several disadvantages attendant with the standard vessel construction above-described. For example, cargo carried within the wing tanks or other tanks capable of holding cargo may be intimately intermingled with the intricate truss and support structures supporting the inner and outer plating of the vessel. This makes it difficult to carry other than a particular type of cargo within the wing tank volume. As stated, typically this cargo is molasses, lard oil, or petroleum. If, for any reason, the outer side shell or outer bottom loses its integrity, the cargo carried therewithin may escape with the consequential deleterious environmental aftermath associated with a spill. Further, loss of integrity of the kind discussed immediately above may expose the unloading apparatus to the external environment. The possibility then exists that water could enter the inner storage volumes through the unloading apparatus and thereby add appreciably to the weight of the vessel, possibly to the extent that the vessel may sink. Due to the interconnection of the cargo volumes through the unloading apparatus and the possibility of sinking if the integrity of the vessel is lost, prior art vessels require complex and expensive safety apparatus to guard against such occurrence.
Furthermore, it is difficult and expensive with vessels of the present construction to economically transport heated cargos such as hot asphalt and the like. Since such cargos must be heated in order to pump or otherwise remove them from the interior volumes of the vessel, it is necessary in the usual case to add heat to such cargo. This requirement further increases the expense of transport.
It is believed to be advantageous to provide a cargo transport system adaptable for barge, rail, truck, or other transportation modes wherein a container having a cargo carrying volume therein is movably disposed with respect to a receptacle such that a separate, commercially significant cargo receiving volume may be defined between the container and the receptacle when the container is in an elevated position. The cargo receiving volume may advantageously be utilized to transport a cargo dissimilar to the cargo carried within the container without risk of contamination thereby. It is also of advantage to provide an arrangement whereby the container may be lifted to an elevation to define a cargo receiving volume such that, when a cargo is disposed therein, the lower surface of the container operates to minimize free surface effects of the cargo. The lifting arrangement may be disposed on the carrier itself or the container may be provided with a connection arrangement to connect the container with a lifting arrangement disposed elsewhere. It would be of further advantage to utilize guide members adaptable to guide the movement of the container and, in connection with several arrangements of the guide member, serve to limit the shifting of a cargo within the cargo receiving volume.
The receptacle may be sized to receive the container such that a residual volume is defined between the container and the receptacle when the container is in a lowered position. The residual volume is combinable with the enlargement volume generated when the container is elevated to define the cargo receiving volume.
In view of the foregoing, it would also be advantageous to provide a cargo transport system having the container closely fitted within a receptacle formed by a continuous sleeve and bottom closure. Either the container or the receptacle or both may be insulated to carry hot cargos with a minimum of heat loss. Through the provision of an independent movable container, insulation of an entire bounding surface is expeditiously permitted to thereby facilitate carriage of a heated cargo. As a result, it is believed possible to avoid the heat loss from the material being transported in a manner more efficient than that known to the prior art. Furthermore, relatively little, if any, additional heat need be added to pump or otherwise remove certain cargo, such as asphalt, from the vessel.
The provision of the relatively movable container supported within the carrier itself permits the cargo carrying volume and the cargo receiving volume (defined respectively on the interior of the container and between the exterior of the container and the receptacle) to exhibit relatively smooth surface areas. The intermingling of cargo with the support structure of the vessel itself is thus avoided.
By the provision of the container/receptacle arrangement, the risk of spills is minimized. For example, in the event of a rupture or leak of the container, cargo carried therewithin is confined within the receptacle. Further, if the receptacle is disposed within plating other than side and bottom shell plating and if the receptacle leaks, the cargo contained therewithin still is confined to the interior of the barge shell.
Further advantage would be gained by the provision of containers of substantially standard size so that manufacture of the containers is expedited. Standardization enhances the transferability of cargos from, for example, a waterborne barge to an onshore rail transport, with a minimum of cost. Furthermore, standardization facilitates removal and repair of a faulty container yet permits a substitute therefor to be readily provided into the cargo transport vessel. Standardization also permits the carriage of different types of cargos by replacement of containers; for instance, the conversion of the barge from asphalt service to vegetable oil service could be achieved by removing the insulated asphalt container and installing a differnt container for vegetable oil with a suitable coating on the inside.
It would be of further advantage to provide the container and/or the receptacle with a geometry such as right-circular cylinders, right-elliptical cylinders, spheres and hemispheres, or ellipsoid and hemiellipsoids such that stress concentration factors attendant with geometries used by carriers (generally rectangular in configuration) are substantially reduced. Therefore, concern for expansion and contraction caused by thermal changes and transit conditions (such as waves or rail discontinuities) are believed to be effectively eliminated with the cargo transport system embodying the teachings of this invention.